kearsley



July 20 1926;" Re. 16,386

W. K. KEARS LEY, JR IBTHOD OF AND APPARATUS FOR AUTOIATICALIQY REMOVING GASES Origin Filed Nov. 29 19 Inventor William K. Kearsley, Jr.

xwAaxk;

His Attorney,

v Io. 1,357,110,

The present invention comprises a method 111d. .ap aratus for treating electrical discharge evices such, for example, as X-ray tubes, in order to free the same from gases I which would be disengaged during the oper- :fion of the device and become ionized,

.reby interfering with the-desired functio of the device. l li tie preparation of a device to be oper- 10 ated with a substantially pure electron discharge, it is necessary not only to remove iron: the space within said device but the metal parts, particularly the rodes and from the walls of the globe. J51 accordance with mv invention these are removed while the device is operdevice. novel featuresof mywinbe set forth with particularity .inthe appended claims. i ,1 accompanying drawing illustrates diagrammatically an apparatus embodying any invention. -Beferring to the drawing the device .shown in' connection with my invention-is an X-ray tube comprisi an envelop 1 containi a cathode 2 an an anode 3, the e-being surrounded by a discharge 80 control focusing member which is elecconnected to the cathode, as shown.

The cathode and anode are connected respect'rvely by conductors 5 and 6 to the high potential secondary of a transformer 7. The rimaries of the transformer are connected vconductors 8 and 9 in series with an 'c resistance 10, to current supply mains 11 and 12., Thecathode 2 of the X-ray tube is connected by conductors 5 and 13 to low voltage secon ary of a small transformer 14 in order to furnish heating current. for 0 rating the cathode at incandesoence. e primary of transformer 2 thep'rimarywin g of the transformer '7, the voltage 'of' the'cathode heating current hence being proportional ,to the voltage of the main supply circuit, as modified by the v drop, in resistance device 10. -In the particular apparatus illustrated the of the trans ormer 14 is connected Ito the outer terminals of turns of the prigniaryf windiugeoftransformer 7 which are .to I

turns connected to the sup Reiaued July 20, 1926. 1 f 1 ":1:

un A, pmthepump and the energy input is. Iulated to prevent damage I 14 isconnected hgnoonductors 15 and 16 to PATENT orFlcE.

mnsnnv, JR, 0] SCHENECTADY, NEW YORK, ASSIQN'OE IIIO GENERAL ELECTRIC COIPANY, A CORPORATION OF NEW YORK.

Inc-non or Ann arrm'ru's FOB auroma'rrcaur nnnovmc oasns.

dated .lovember 2, 1920, Serial Kc; 284,685, filed November 29, 1918. Application for rclslue fled September 11, 1922. Serlal No. 587,586.

ply Wires 8 and 9. This connection gives a somewhat higher voltage for feeding the transformer 14 and will vary with the particular voltage relation of the main transformer and the cathode heating transformer.

The device to be evacuated is connected by suitable tubing 18 to a pump, which is constantly maintained in operation during the evacuation process. After the X-ray tube or other hot cathode device which is being evacuated has been given the usual preliminary exhaust during which operation the envelop is heated nearly to the softening point of glass the cathode is heated to incandescence and energy is impressed upon the cathode and anode, for example, by closing the'switch 20, thereby sending an e ec-tron current from the cathode to the anode. The action of the current upon the anode causes some gas to be liberated which becomes ionized, and causes the current carrying capacity of the tube to increase. The ionization of the gas produces positive ions which reduce the current-limiting effect of the negative electrons upon each other, or, in other words, reduce the space charge in the tube. This has the effect of decreasing the voltage drop between cathode and anode and permitting a greater current to flow. When the transformer furnishes a greater current to the tube a larger current must "flow through'the resistance 10 thereby producing an increased voltage drop across the terminals of this resistance and reducing the voltage impressed upon the primary winding of the transformer. The result of this is to decrease the voltage both at the terminals of the secondary of the transformer 7 and the voltage of the terminals of the transformer 14. The reduction in voltage at the terminals of the transformer 14 causesa reduced heating current to be delivered to the cathode tube, thereby lowering the temperature of the cathode and decreasing the electron emission. This decreased electron emission therefore opposes the tendency for a greater current to flow through the tube so that the equilibrium is estahhshed with a fiow' through the tu The 0 ration of the pump having in the meanwhile continued the liberated gases are progressively removed until the voltage gzeatly decreased energy drop between cathode and anode is reestablished. The resulting increase of the potential of the heating current for the cathode increases the cathode temperature and hence the electron emission from the cathode. The voltage of the transformer 7 builds up until the voltage drop between cathode and anode again becomes high enough to cause the electron stream to be delivered with sufficiently high velocity to the anode to disengage an additional amount of gas, causing the above described process to be repeated. In this manner the evacuation of the tube with the removal of gas from the anode and other parts of the tube proceeds automatically without any danger of injury by excessive flow of current, until the Xsray tube operates continuously unaccompanied by the disengagement of gas and accompanying posi tive ionization. The tube may then be sealed oil from the pump.

What I claim as new and desire to secure by Letters Patent of the United States, 1s:

1. The method of preparing an X-ray tube containing a cathode the electron emission of which is variable independentl of ,passage of current through said tube w ich consists in passing energy through said tube from a source of energy the voltage of which varies in a sense inversely with the am rage, varying the electron emission of cathode inversely with the amperage of the current through said tube and coincidentally removing from said tube gas liberated by said passage of energy.

2. The method of preparing an electrical discharge apparatus containing a cathode operating at incandescence which consists in operating said device with current, the voltage of which varies in an inverse sense with the amperage, varying the temperature of the cathode of said device directly with the voltage of said current, and coincidentally continuing the removal of gas.

3. An apparatus for removing gas from an incandescent cathode discharge apparatusicomprising a source of electric energy for operating said device, the voltage of .which varies in an inverse sense with the -rage, means for heating the cathode of sai device by current varying directly with the voltage of said-source, and means for removing gases from said device.

, 4. An apparatus for automaticall controlling the operation of an incan escent cathode vacuum device during evacuation comprising a high potential transformer adapted to supply operating current for said device, an ohmic resistance in the rimary circuit of said transformer, a ow potential transformer for heating the oathodeof said device, means for supplying said second transformer with current from the primary circuit of said high potential transformer,iand means for removing gases from said device disengaged by the conduction of energy therethrough.

5. An apparatus for preparing an=incandescent cathode device for operation with a substantially pure electron discharge comprising means for supplying an operating current to said device the voltage of which varies substantially inversely with the amperage, means for automatically varying the temperature of the cathode of said device inversely with an increase of amperage of said operating current, and meansfor removing gases liberated durin operation.

6. The method of controlling the energy input of an incandescent cathode device during exhaust which consists in reducing the operating voltage as the current carrying capacity of said device increases by the disengagement of gas and coincidently reducin the cathode temperature.

The step in the method of controlling the energy input of an incandescent cathode device during exhaust which consists in reducing the cathode temperature in step with an increase of current carrying capacity of said device due to gas evolution.

8. An electron discharge apparatus comprising the combination of a supply circuit, a voltage-consuming device in said circuit, a vacuum tube having a cathode rendered operative by heating, connections for deriving both an electron current and a cathode heating current for said tube from said circuit in series with said voltage-consuming device, said device being adapted to consume a voltage varying in value directly with the current traversingthe same.

9. An electron discharge apparatus comprising the combination of a supply circuit, an ohmic resistance device in said circuit, a vacuum tube having a cathode rendered operative by heating, connections for deriving both an electron current and a cathode heating current for said tube from said circuit in series with said voltage consuming device, said device being adapted to consume voltage varying in value directly with the current traversing the same.

10. An X-ray system comprising a supply circuit, a resistance device in said circuit, an X-ray tube having a cathode having an activating circuit, means for deriving a main operating current for said X-ray tube in series with said device from said supply circuit and means for deriving from said circuit also a cathode activating current which is modified in voltage by the consumption of voltage in said resistance device.

11. An X-ray system comprising the com-' bination of a supply circuit, an incandescent cathode X-ray tube having main electrodes connected to derive current from said circuit, voltage regulating means in said sup-ply circuit sai means being constructed to produce a drop of voltage which increases directly with an increase of current transmitted by said tube, and means for heatin the cathode of said tube by current transmitted by said means.

12. An X-ra a paratus comprising an incandescent cat 0 e X -ray device, a transformer operatively connected to said device, a second transformer connected to the cathode of said device, a common suppl circuit for both said transformers, and an 0 io resistance device in said supply circuit.

13. An X-ray system comprising the combination of a supply circuit, an incandescent cathode X-ray tube having main electrodes connected to derive current from said circuit, voltage regulating means in said supply circuit, said means being constructed to consume voltage varying directly with the variation of current transmitted by said N tube, and means for heating the cathode of said tube by current transmitted by said means.

14. An X-ray apparatus comprising a supply circuit, an incandescent cathode X- as ray device connected to derive current from said circuit, a resistance device in said circuit and means for heating the cathode of said device by current having a voltage proportional to the difference between the voltage of said supply circuit and the drop of WILLIAM K. KEARSLEY, JR. 

